The American held off a late challenge from Japan's Masato Sakai to win the 200m butterfly in a time of 1:53.26, before seeing the US home on the final leg of the 4x200m freestyle relay, with the US finishing almost three seconds ahead of silver medallists Great Britain.

Elsewhere in the pool, Phelps' compatriot Katie Ledecky won her second gold of the Games, edging out Sweden's Sarah Sjostrom in the 200m freestyle final in a time of 1:53.73. American Ledecky was just outside world record pace, but managed to hold off a spirited effort by Sjostrom.

Williams, who won her sixth Wimbledon championship this summer, was denied the opportunity to win her fifth medal at the Olympic Games. Serena and Venus exited the doubles tournament in the first round on Sunday, losing to Czech pair Lucie Safarova and Barbora Strycova.

The Brave Blossoms' shock 14-12 victory echoed Japan's famous victory over South Africa in the 15-a-side World Cup last year, the biggest shock the sport has ever seen.

"It's unbelievable, you never see a minnow team come here and beat a team supposed to be a gold medal contender," said Japan's New Zealand-born playmaker Lomano Lemeki.

Spanish basketball team suffer more heartache

There was a Brazilian celebration in men's basketball after Marcus Marquinhos' offensive rebound tip-in with 5.5 seconds left in the game gave the host team a 66-65 win over Spain. The boisterous crowd erupted with a deafening, flag-waving celebration.

The Spanish team - silver medalists in 2008 and 2012 - fell to a disappointing 0-2 start to the Rio Games, following a narrow defeat by Croatia in their first game.

The German women's team have never done better than three consecutive bronze medals won between 2000 and 2008 and will do well to make it back to the podium after taking just four points from their three Group F games.

Meanwhle, reigning Olympic champions USA were held to a 2-2 draw with Colombia, but the US were already safely through.

Deng leads the Wei in weightlifting

Deng Wei of China captured gold in the women's 63-kilo category with two world record lifts.

The world ranking leader Deng had 115kg in the snatch and added a world record 147kg in the clean and jerk for a winning total 262kg, also a world record.

"At the very beginning, as this was my first Olympic Games, I was quite nervous, but I set my goal before coming to Rio to set the world record, so it was actually within my expectations," Deng said.

Germany's Karsch wins silver

Monika Karsch of Germany was edged into silver medal position by Greek shooter Anna Korakaki, who took the gold medal in the women's 25 metre pistol event.

Korakaki had been one point from an Olympic gold medal, leading 6-0, in the women's 25-meter pistol final on Tuesday but began to choke. She hit a wrong target and missed one completely, allowing Karsch to draw level at 6-6.

Karsch started the seventh five-shot series hitting the wrong target, allowing Korakaki to win gold.

Karsch started the seventh five-shot series hitting the wrong target, and Korakaki retook the lead going to the last shot.

Murray and Nadal through, but Muguruza slump continues

Garbine Muguruza's post-French Open slump continued Tuesday when she crashed out of the Olympics, while Andy Murray and Rafael Nadal made the third round.

Third seed Muguruza slipped to a worrying 6-1, 6-1 loss to Monica Puig of Puerto Rico, the world number 34. Murray raced into the last 16, blitzing Juan Monaco of Argentina 6-3, 6-1. Nadal was equally ruthless, claiming a seventh win in eight clashes against Italy's Andreas Seppi 6-3, 6-3.